/*-
 * #%L
 * HAPI FHIR - Client Framework
 * %%
 * Copyright (C) 2014 - 2025 Smile CDR, Inc.
 * %%
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 * #L%
 */
package ca.uhn.fhir.rest.client.method;

import ca.uhn.fhir.context.ConfigurationException;
import ca.uhn.fhir.context.FhirContext;
import ca.uhn.fhir.i18n.Msg;
import ca.uhn.fhir.model.api.IResource;
import ca.uhn.fhir.model.valueset.BundleTypeEnum;
import ca.uhn.fhir.parser.IParser;
import ca.uhn.fhir.rest.api.Constants;
import ca.uhn.fhir.rest.api.MethodOutcome;
import ca.uhn.fhir.rest.client.exceptions.InvalidResponseException;
import ca.uhn.fhir.util.BundleUtil;
import ca.uhn.fhir.util.ReflectionUtil;
import org.hl7.fhir.instance.model.api.IBaseBundle;
import org.hl7.fhir.instance.model.api.IBaseOperationOutcome;
import org.hl7.fhir.instance.model.api.IBaseResource;

import java.io.IOException;
import java.io.InputStream;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;

public abstract class BaseResourceReturningMethodBinding extends BaseMethodBinding<Object> {
	protected static final Set<String> ALLOWED_PARAMS;
	private static final org.slf4j.Logger ourLog =
			org.slf4j.LoggerFactory.getLogger(BaseResourceReturningMethodBinding.class);

	static {
		HashSet<String> set = new HashSet<String>();
		set.add(Constants.PARAM_FORMAT);
		set.add(Constants.PARAM_NARRATIVE);
		set.add(Constants.PARAM_PRETTY);
		set.add(Constants.PARAM_SORT);
		set.add(Constants.PARAM_SORT_ASC);
		set.add(Constants.PARAM_SORT_DESC);
		set.add(Constants.PARAM_COUNT);
		set.add(Constants.PARAM_OFFSET);
		set.add(Constants.PARAM_SUMMARY);
		set.add(Constants.PARAM_ELEMENTS);
		ALLOWED_PARAMS = Collections.unmodifiableSet(set);
	}

	private MethodReturnTypeEnum myMethodReturnType;
	private Class<?> myResourceListCollectionType;
	private String myResourceName;
	private Class<? extends IBaseResource> myResourceType;
	private List<Class<? extends IBaseResource>> myPreferTypesList;

	@SuppressWarnings("unchecked")
	public BaseResourceReturningMethodBinding(
			Class<?> theReturnResourceType, Method theMethod, FhirContext theContext, Object theProvider) {
		super(theMethod, theContext, theProvider);

		Class<?> methodReturnType = theMethod.getReturnType();
		if (Collection.class.isAssignableFrom(methodReturnType)) {

			myMethodReturnType = MethodReturnTypeEnum.LIST_OF_RESOURCES;
			Class<?> collectionType = ReflectionUtil.getGenericCollectionTypeOfMethodReturnType(theMethod);
			if (collectionType != null) {
				if (!Object.class.equals(collectionType) && !IBaseResource.class.isAssignableFrom(collectionType)) {
					throw new ConfigurationException(Msg.code(1458) + "Method "
							+ theMethod.getDeclaringClass().getSimpleName() + "#" + theMethod.getName()
							+ " returns an invalid collection generic type: " + collectionType);
				}
			}
			myResourceListCollectionType = collectionType;

		} else if (IBaseResource.class.isAssignableFrom(methodReturnType)) {
			if (Modifier.isAbstract(methodReturnType.getModifiers()) == false
					&& theContext
							.getResourceDefinition((Class<? extends IBaseResource>) methodReturnType)
							.isBundle()) {
				myMethodReturnType = MethodReturnTypeEnum.BUNDLE_RESOURCE;
			} else {
				myMethodReturnType = MethodReturnTypeEnum.RESOURCE;
			}
		} else if (MethodOutcome.class.isAssignableFrom(methodReturnType)) {
			myMethodReturnType = MethodReturnTypeEnum.METHOD_OUTCOME;
		} else {
			throw new ConfigurationException(Msg.code(1459) + "Invalid return type '"
					+ methodReturnType.getCanonicalName() + "' on method '" + theMethod.getName() + "' on type: "
					+ theMethod.getDeclaringClass().getCanonicalName());
		}

		if (theReturnResourceType != null) {
			if (IBaseResource.class.isAssignableFrom(theReturnResourceType)) {
				if (Modifier.isAbstract(theReturnResourceType.getModifiers())
						|| Modifier.isInterface(theReturnResourceType.getModifiers())) {
					// If we're returning an abstract type, that's ok
				} else {
					myResourceType = (Class<? extends IResource>) theReturnResourceType;
					myResourceName = theContext.getResourceType(myResourceType);
				}
			}
		}

		myPreferTypesList = createPreferTypesList();
	}

	public MethodReturnTypeEnum getMethodReturnType() {
		return myMethodReturnType;
	}

	@Override
	public String getResourceName() {
		return myResourceName;
	}

	/**
	 * If the response is a bundle, this type will be placed in the root of the bundle (can be null)
	 */
	protected abstract BundleTypeEnum getResponseBundleType();

	public abstract ReturnTypeEnum getReturnType();

	@Override
	public Object invokeClient(
			String theResponseMimeType,
			InputStream theResponseInputStream,
			int theResponseStatusCode,
			Map<String, List<String>> theHeaders)
			throws IOException {

		if (Constants.STATUS_HTTP_204_NO_CONTENT == theResponseStatusCode) {
			return toReturnType(null);
		}

		IParser parser = createAppropriateParserForParsingResponse(
				theResponseMimeType, theResponseInputStream, theResponseStatusCode, myPreferTypesList);

		switch (getReturnType()) {
			case BUNDLE: {
				IBaseBundle bundle;
				List<? extends IBaseResource> listOfResources;
				Class<? extends IBaseResource> type =
						getContext().getResourceDefinition("Bundle").getImplementingClass();
				bundle = (IBaseBundle) parser.parseResource(type, theResponseInputStream);
				listOfResources = BundleUtil.toListOfResources(getContext(), bundle);

				switch (getMethodReturnType()) {
					case BUNDLE_RESOURCE:
						return bundle;
					case LIST_OF_RESOURCES:
						if (myResourceListCollectionType != null) {
							for (Iterator<? extends IBaseResource> iter = listOfResources.iterator();
									iter.hasNext(); ) {
								IBaseResource next = iter.next();
								if (!myResourceListCollectionType.isAssignableFrom(next.getClass())) {
									ourLog.debug(
											"Not returning resource of type {} because it is not a subclass or instance of {}",
											next.getClass(),
											myResourceListCollectionType);
									iter.remove();
								}
							}
						}
						return listOfResources;
					case RESOURCE:
						List<IBaseResource> list = BundleUtil.toListOfResources(getContext(), bundle);
						if (list.size() == 0) {
							return null;
						} else if (list.size() == 1) {
							return list.get(0);
						} else {
							throw new InvalidResponseException(
									Msg.code(1460)
											+ "FHIR server call returned a bundle with multiple resources, but this method is only able to returns one.",
									theResponseStatusCode);
						}
					default:
						break;
				}
				break;
			}
			case RESOURCE: {
				IBaseResource resource;
				if (myResourceType != null) {
					resource = parser.parseResource(myResourceType, theResponseInputStream);
				} else {
					resource = parser.parseResource(theResponseInputStream);
				}

				MethodUtil.parseClientRequestResourceHeaders(null, theHeaders, resource);

				return toReturnType(resource);
			}
		}

		throw new IllegalStateException(Msg.code(1461) + "Should not get here!");
	}

	private Object toReturnType(IBaseResource resource) {
		Object retVal = null;

		switch (getMethodReturnType()) {
			case LIST_OF_RESOURCES:
				retVal = Collections.emptyList();
				if (resource != null) {
					retVal = Collections.singletonList(resource);
				}
				break;
			case RESOURCE:
				retVal = resource;
				break;
			case BUNDLE_RESOURCE:
				retVal = resource;
				break;
			case METHOD_OUTCOME:
				MethodOutcome outcome = new MethodOutcome();
				outcome.setOperationOutcome((IBaseOperationOutcome) resource);
				retVal = outcome;
				break;
		}
		return retVal;
	}

	@SuppressWarnings("unchecked")
	private List<Class<? extends IBaseResource>> createPreferTypesList() {
		List<Class<? extends IBaseResource>> preferTypes = null;
		if (myResourceType != null && !BaseMethodBinding.isResourceInterface(myResourceType)) {
			preferTypes = new ArrayList<Class<? extends IBaseResource>>(1);
			preferTypes.add(myResourceType);
		} else if (myResourceListCollectionType != null
				&& IBaseResource.class.isAssignableFrom(myResourceListCollectionType)
				&& !BaseMethodBinding.isResourceInterface(myResourceListCollectionType)) {
			preferTypes = new ArrayList<Class<? extends IBaseResource>>(1);
			preferTypes.add((Class<? extends IBaseResource>) myResourceListCollectionType);
		}
		return preferTypes;
	}

	/**
	 * Should the response include a Content-Location header. Search method bunding (and any others?) may override this to disable the content-location, since it doesn't make sense
	 */
	protected boolean isAddContentLocationHeader() {
		return true;
	}

	protected void setResourceName(String theResourceName) {
		myResourceName = theResourceName;
	}

	public enum MethodReturnTypeEnum {
		BUNDLE_RESOURCE,
		LIST_OF_RESOURCES,
		METHOD_OUTCOME,
		RESOURCE
	}

	public static class ResourceOrDstu1Bundle {

		private final IBaseResource myResource;

		public ResourceOrDstu1Bundle(IBaseResource theResource) {
			myResource = theResource;
		}

		public IBaseResource getResource() {
			return myResource;
		}
	}

	public enum ReturnTypeEnum {
		BUNDLE,
		RESOURCE
	}
}
